The recent emergence of specialty cardiac hospitals has generated widespread controversy. Proponents suggest that such hospitals deliver higher quality and lower cost care, while critics contend that specialty lospitals "cherry pick" lower severity and more profitable patients with no demonstrable improvements in patient outcomes. Prior studies comparing specialty cardiac and general hospitals have examined a limited number of conditions and procedures, have included relatively few specialty hospitals, and have not examined the impact of specialty hospitals on general hospitals in the same healthcare markets. The results of these preliminary studies have been inconsistent with some studies demonstrating improved outcomes in specialty hospitals and others demonstrating no improvement. Moreover, these initial studies have been based exclusively upon administrative data sources and have not utilized clinical registries despite the potential advantages of this approach. The specific aims of the proposed research are to compare the outcomes of patients receiving care in specialty cardiac and competing general hospitals and to examine the impact of specialty hospitals on general hospitals in the same markets. This four-year study will involve the analysis two administrative data sources (national Medicare and state-level claims data) supplemented by two proprietary clinical registries (the Society for Thoracic Surgeons National Database and the National Cardiovascular Data Registry). The research will address the limitations of prior studies by examining outcomes of patients treated in a larger number of specialty cardiac hospitals for a broad spectrum of conditions, including patients with acute myocardial infarction and congestive heart failure and patients undergoing percutaneous coronary interventions, coronary artery bypass graft surgery, and valve replacement surgery using both administrative and clinical data. For each diagnosis, mortality and complication rates in specialty cardiac hospitals will be compared with mortality and complication rates in competing general hospitals located within the same healthcare market as the specialty hospitals. Three complementary methods will be used to minimize selection bias (hierarchcial linear models, propensity scores, and instrumental variables) and adjust for important patient-level, hospital-level, and market-level confounders. Additional analyses will assess the impact of new specialty cardiac hospitals on the cardiac volumes and patient outcomes of competing general hospitals located within the same healthcare markets. Together these analyses will provide much needed information on the relative quality of care provided by specialty cardiac hospitals to policy makers, payors, providers and patients.